KTM used to be dead last in suspension
ranking. Now they are near the top.
( 9) Frame guards. Some test riders complained that their boots caught
on the edge of the guards, while others think that the guards move their
feet out too far. We removed them
and replaced them with either Nihilo
frame tape or nothing (except a can of
( 10) Shock collar. We hate this
shock collar. Sometimes it works
and sometimes it doesn’t. KTM
warns against hitting it with a
hammer and a punch, but we really want to hit it with something.
THE BURDEN OF WEIGHT
The 2017–’ 18 KTM 450SXF hits
the scale at 222 pounds. That is a
shockingly light number. The closest Japanese-built 450 is 9 pounds
heavier and several are 16 or more
pounds heavier. You could buy all the
titanium in the world, but your bank
account will run out of money before
you get a 2017 Yamaha YZ450F, 2017
Suzuki RM-Z450 or an electric-start
2018 Honda CRF450 in the parking lot
of the same ballpark.
TAKE CARE WITH THE FORK
The fork-bleed screws on the 2017–
’ 18 KTM 450SXF are a mismatched
combination. The air side of the WP
AER forks is bled with either a #20
Torx wrench or a 10mm T-handle.
Even if you own a #20 Torx wrench,
never use it on the aluminum air-bleed
screw. Why not? It will strip out of the
soft aluminum. Instead, use a 10mm
T-handle. On the left non-air fork cap,
you have to use the #20 Torx, but at
least this screw is made from steel. On
the left side we replaced the #20 Torx
with the Phillips head screws from a
previous-model KTM 4CS fork.
Set the air pressure in the WP AER forks
first and then tune with the clickers.
KTM 450SXF AER FORK
The trick to getting the most from
your AER air forks is to find the proper air pressure for your weight, speed
and track. We typically start with the
OEM-recommended air pressure and
then lower it in 2-psi increments. How
do we know when we have the proper
pressure? We lower the air pressure to
the point where the forks are almost
getting full travel. We don’t want them
to bottom completely, but we also
don’t want them to feel like they are
dropping into their stroke. Typically,
the AER forks ride high in their stroke
with the stock air pressure.
Slower or lighter riders might have
to lower the oil height in the damping
leg by 10cc or more to get full travel.
Additionally, the air pressure goes up
as the ambient temperature rises. In
these cases, just reset the air pressure
to your chosen setting between motos.
It should be noted that if you ride long
motos, the air pressure will rise by 4
psi because of internal friction. We
bleed the outer chambers regularly.
Don’t be afraid to go down on the air
pressure just because the manual says
to run 156 psi. We use a zip-tie on the
fork leg to see how much travel we
are getting. We lower the air pressure
until we have 1.5 inches of travel left
to the zip-tie. We have riders who
run as low as 135 psi. Once you find
the right air pressure for you, use the
clickers to dial in the feel.
Given an unlimited budget, most
MXA test riders choose to run WP’s
aftermarket Cone Valve forks. These
are the equivalent of Showa A-Kit
works forks. WP Cone Valve forks
come in both AER air and coil spring
versions. We prefer the spring models,
but they weigh 3 pounds more.
For hardcore racing, we recommend
this fork setup
Spring rate: 135 psi (Novice), 145
psi (Intermediate), 150 psi (Expert)
Compression: 15 clicks out
Rebound: 15 clicks out
Fork-leg height: Third line
KTM 450SXF WP SHOCK
The 2017–’ 18 KTM 450SXF comes
with a 45 N/m shock spring. This is
a big improvement over the 48 N/m
shock spring from 2016; however,
shock springs come in different spring
rates to meet the weight, speed and
track demands of individual riders.
Thus, if you are heavier than 190
pounds or faster than the average
rider, you might be a candidate for the
48 N/m spring.
We turn the high-speed compression damping in a little to lessen
G-outs and run more rebound than the
recommended setting. Additionally,
we set the sag at 105mm instead of
the WP-recommended 110mm. We run
the low-speed compression at 15 out,
the high-speed compression at 1-3/4
turns out and the rebound on 10.
When we have issues, we start with
the high-speed adjuster first and then
move to the low-speed clicker.
When we need to adjust the preload
on the rear shock, we do not hit the
red Nylon shock collar with a hammer.
Instead, we turn the shock spring by
hand while using a long flat-bladed
screwdriver to pry against the frame
and the shock collar at the same time.
If you hit the nylon shock collar with
a hammer and punch, you will deform
For hardcore racing, we recommend
this shock setup for the 2017 KTM
450SXF (stock specs are in parentheses).
Spring rate: 45 N/m
Race sag: 105mm (110mm)
Hi-compression: 1-3/4 turns out
( 2 turns out)
Lo-compression: 15 clicks out
Rebound: 10 clicks out ( 15 clicks
The one-piece top bar clamp can and
will twist in crashes. We know.